Purpose The purpose of the study was to investigate the effect of vibratory stimulus on the static postural control of 8 healty senior adults. Methods To achieve this goal, all subjects participated in two different kinds of static postural control tasks. Task 1 was a static postural control task, where both-legs stand on the ground. Second task was an unstable static postural control task using only single leg stance. As they maintain their balance, 6 different vibratory stimulus were provided on the sole of their feet(personal threshold 0%, 80%, 90%, 100%, 110%, 120%). Results The results of the study were as follows: First, there was no significant differences in postural control ability according to different types of vibrator intensity. Second, there was a significant difference in single-leg postural control ability according to vibrator intensity. Third, there was a significant difference in anterio-posterior stability according to the different types of vibrator intensity. Conclusion Stochastic resonance using vibratory stimulus was more effective in the single leg stance task, rather than the double leg stance task. Moreover, sub-threshold vibratory stimulus(80%, 90%) intensity were more effective than higher vibratory stimulus(100%, 110%, 120%).
The human foot is only part that directly contact between the body and the external environment, and is ideally positioned to provide sensory information to the Central Nervous System (CNS) during static and dynamic tasks. Through cutaneous mechanoreceptors located in the dermis, the foot is able to recognize touch pressure and vibration stimuli, which provide important feedback information used for the fine coordination of movements. The purpose of this study is to quantitatively examine the effect of changing the foot cutaneous sensory by temperature stimulus on maximal performance and muscle activation using wavelet technique. Sixteen healthy subjects volunteered to participate in this study (Male: Age 21.4±2.4years; Height 174.7±5.3츠; Weight 70.6±5.2kg; Female: Age 20.5±0.6years; Height 163.2±3.1cm; Weight 55.6±4.8kg). Sensory pressure thresholds were determined for the plantar surface of the foot using monofilament. Kinematic, kinetic and EMG data which relative to maximal performance were collected while squat jumping in each temperature condition(cool 12-15℃ normal 28-30℃ hot 45-48℃). Maximal jump height was significant higher in normal condition. Vertical GRF in normal condition showed higher peak value the other conditions. And then EMG signal were significant different between temperature conditions during maximal performance. By changed sensory feedback on temperature, one can alter maximal performance and muscle activation pattern. Cutaneous feedback is important in performance and neuromuscular control, and temperature changes significantly influence on lower extremity during maximal squat jump performance of healthy subjects.
